Bistable Electromagnetic Clutch: Efficient And Safe

Electromagnetic tooth clutches consume electrical energy either in the closed state - that is to say torque-transmitting - or in the open state, which is the current state of the art. To maintain a switching state (open or closed), energy is permanently required.

One consequence of this is that an unintentional change in the switching state of the clutch can occur in the event of a power failure. Depending on the application, this can be regarded as extremely critical for security reasons.

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The new development of the Mönninghoff machine factory offers two decisive advantages over conventional electromagnetic tooth clutches: A short current pulse is only required to change the switching state. The switching state is maintained without current, regardless of whether the clutch is open or closed. This means that large amounts of electrical energy can be saved in most applications.

The second advantage is that even in the event of a power failure, the clutch is in the current switching state. There is therefore no unintentional opening or closing of the coupling, which means a considerable gain in safety in numerous applications and also takes into account the requirements of the new machine directive 2006/42 / EC.

The clutch holds spring force

These advantages are realized by means of a functional principle consisting of a combination of an electromagnetic coil, permanent magnets and coil springs. The spring force alone keeps the clutch open. However, the spring forces are overcome and the clutch closes by a current pulse on the electromagnetic coil. In the following, closed state, the spring force is overcome solely by the force of the permanent magnets and the clutch is kept in the closed state. The force of the permanent magnets is dimensioned so that the nominal torque of the clutch can also be transmitted. All that is needed to open the clutch is a short current pulse, now in a different current direction, onto the electromagnetic coil.As a result, the force of the permanent magnets is neutralized and the clutch is opened again by the spring force.

Special solutions are also possible

Both the outside diameter and the transferable torque largely correspond to the standard couplings of the Mönninghoff machine factory. The length of the coupling alone differs from the standard. To detect the switching state, there is a groove on the anchor part of the coupling as standard, which can be queried with a commercially available inductive sensor or the like. In addition to the bistable electromagnetic clutch, bistable tooth brakes and various other special designs are also possible according to customer requirements. Possible areas of application include mobile applications in which only a limited amount of energy is available, but also safety-relevant applications in which the clutch does not change its switching state even in "emergency situations". (ud)